A control surface actuator must respond to performance requirements (speed and loading to counter the aerodynamic loading applied on the associated control surface) without, however, getting damaged, and without damaging the structure on which it acts or on which it is mounted.
On account of its technology, such an actuator is capable of locally producing more loading than the maximum level necessary for its operation. The risk therefore exists that the structure on which the actuator is mounted is subjected to more sizable loadings than the level for which it was dimensioned. Hence, to protect this structure, the actuators are, generally, equipped with a passive mechanical device for commanding loading, namely an overpressure valve of PRV (“Pressure Relief Valve”) type, which limits the loading generated by the actuator.
However, with such a device, the loading produced or taken up by the actuator is dependent on the speed of the actuator. Hence, when the loading produced or taken up by the actuator is greater than the loadings that can be supported by the associated structure, this passive loading commanding device is not sufficient, because of its dependency with the speed of the actuator.
Too sizable a loading produced or taken up by the actuator may in particular be generated by a fault with the control of the actuator, by contact with another surface, by an embarkation of another actuator or by other exterior circumstances.